Biobased Furanics: Kinetic Studies on the Acid Catalyzed Decomposition of 2-Hydroxyacetyl Furan in Water Using Brönsted Acid Catalysts

Sulfonic acid functionalized β zeolite as efficient bifunctional solid acid catalysts for the synthesis of 5-hydroxymethylfurfural from cellulose

Introduction of the sulfonic acid group into H-β zeolite to prepare β-SO₃H bifunctional catalysts for the efficient synthesis of 5-hydroxymethylfurfural (HMF) from cellulose. Catalysts characterization, such as XRD, ICP-OES, SEM (Mapping), FTIR, XPS, N₂ adsorption-desorption isotherm, NH₃-TPD, Py-FTIR demonstrate the sulfonic acid group was successfully grafted onto the β zeolite. A superior HMF yield (59.4 %) and cellulose conversion (89.4 %) was obtained in the H₂O(NaCl)/THF biphasic system under 200 °C for 3 h with β-SO₃H(3) zeolite as catalyst. More valuable, β-SO₃H(3) zeolite converts other sugars and obtains ideal HMF yield, including fructose (95.5 %), glucose (86.5 %), sucrose (76.8 %), maltose (71.5 %), cellobiose (67.0 %), starch (68.1 %), glucan (64.4 %) and also converts plant material (25.1 % for moso bamboo and 18.7 % for wheat straw) with great HMF yield. β-SO₃H(3) zeolite catalyst keeps an appreciable recyclability after 5 cycles. Moreover, in the presence of β-SO₃H(3) zeolite catalyst, the by-products during the production of HMF from cellulose were detected, and the possible conversion pathway of cellulose to HMF was proposed. The β-SO₃H bifunctional catalyst has excellent potential for the biorefinery of high value platform compound from carbohydrates.

Chemocatalytic value addition of glucose without carbon-carbon bond cleavage/formation reactions: an overview

As the monomeric unit of the abundant biopolymer cellulose, glucose is considered a sustainable feedstock for producing carbon-based transportation fuels, chemicals, and polymers. The chemocatalytic value addition of glucose can be broadly classified into those involving C-C bond cleavage/formation reactions and those without. The C6 products obtained from glucose are particularly satisfying because their syntheses enjoy a 100% carbon economy. Although multiple derivatives of glucose retaining all six carbon atoms in their moiety are well-documented, they are somewhat dispersed in the literature and never delineated coherently from the perspective of their carbon skeleton. The glucose-derived chemical intermediates discussed in this review include polyols like sorbitol and sorbitan, diols like isosorbide, furanic compounds like 5-(hydroxymethyl)furfural, and carboxylic acids like gluconic acid. Recent advances in producing the intermediates mentioned above from glucose following chemocatalytic routes have been elaborated, and their derivative chemistry highlighted. This review aims to comprehensively understand the prospects and challenges associated with the catalytic synthesis of C6 molecules from glucose.

Preparation of combined cross-linked enzyme aggregates containing galactitol dehydrogenase and NADH oxidase for L-tagatose synthesis via in situ cofactor regeneration

The combined cross-linked enzyme aggregates (combi-CLEAs) containing galactitol dehydrogenase (Gdh) and NADH oxidase (Nox) were prepared for L-tagatose synthesis. To prevent the excess consumption of cofactor, Nox in the combi-CLEAs was used to in situ regenerate NAD⁺. In the immobilization process, ammonia sulfate and glutaraldehyde were used as the precipitant and cross-linking reagent, respectively. The preparation conditions were optimized as follows: 60% ammonium sulfate, 1:1 (molar ratio) of Gdh to Nox, 20:1 (molar ratio) of protein to glutaraldehyde, and 6 h of cross-linking time at 35 °C. Under these conditions, the activity of the combi-CLEAs was 210 U g^-1. The combi-CLEAs exhibited higher thermostability and preserved 51.5% of the original activity after eight cycles of reuses at 45 °C. The combi-CLEAs were utilized for the preparation of L-tagatose without by-products. Therefore, the combi-CLEAs have the industrial potential for the bioconversion of galactitol to L-tagatose.